Prior art U.S. Pat. No. 3,780,634, issued Dec. 25, 1973, discloses a photographic camera which includes a chamber for receiving a film cartridge, a manually rotatable driver engageable coaxially with rotatable film moving means in a light-tight housing of the film cartridge for manually rotating the film moving means to advance or thrust a filmstrip from the housing for exposure in the camera, and locking means for preventing manual rotation of the driver during exposure of the filmstrip. The locking means has a latch pin which is pivoted into an indexing hole in an indexing gear coupled to the driver, to lock the indexing gear and in turn lock the driver. A button connected to the latch pin must be manually depressed to pivot the latch pin out of the indexing hole in the indexing gear to unlock the driver.